Asphalt emulsion priming (AEP) consists of application of a low viscosity asphalt emulsion to an absorbent surface, such as a granular base, in preparation for paving using an asphalt surface course. Road construction typically involves preparation of a surface comprising a granular material, such as sand or gravel, for application of an asphalt surface course. The granular material is often graded and packed to form a relatively flat, uniform surface for paving. The asphalt surface course typically consists of asphalt and an aggregate which is mixed and applied to the surface of the prepared granular material in the road bed.
Asphalt emulsion priming compositions are formulated to penetrate rapidly into the absorbent surface to bind the granular material. Deep penetration is desirable to assure that the primed surface is not easily disrupted by traffic during road surfacing.
In addition to reducing airborne dust generated by wind or by traffic on the granular road surface, AEP provides several benefits. AEP can partially waterproof treated areas to make them resistant to water erosion prior to application of the asphalt surface course. This can reduce or eliminate the need to repair the granular surface after a rainfall. In addition, the AEP can provide an improved bond between the granular base and the asphalt surface course.
AEP compositions presently used typically include a petroleum distillate added to the asphalt. The petroleum distillate lowers the viscosity of the asphalt to improve the penetration of the asphalt into the granular base. One disadvantage of petroleum distillates is that vapors are released into the air as the AEP material sets. This constitutes a significant pollution source and potential health hazard for workers.
In addition, prior AEP compositions typically required an acidic or basic additive, such as hydrochloric acid or sodium hydroxide, to adjust the pH of the composition. These additives can contribute to corrosion of equipment, as well as create personnel safety or environmental concerns.
Accordingly, it is an object of the present invention to provide an AEP composition that does not require use of a petroleum distillate or an additive to adjust the pH of the composition, and has acceptable properties to adequately penetrate a granular surface.
Another object of the present invention is to provide methods of applying the AEP composition to a surface, such as a granular surface being prepared for paving.
Other advantages of the compositions and methods of the present invention will be apparent to those skilled in the art based upon the detailed description of preferred embodiments set forth below.